In my experience, interval training for cardio has the best results. That combines hard running with jogging/walking in-between.

I'm not sure of your cardio experieince. If you are jsut starting out:

Jog for 3 mins
RUN for 1min
Jog/walk fast for 2 min
RUN for 1min
Jog/walk fast for 2 min
(repeat 2 more times)
Jog for 2 mins more

That's 15 of cardio that forces your body into heavier workloads over short periods of time that will burn more fat than 30 mins of just jogging alone.

If you are a more "seasoned" runner, try RUNNING for 1 min and jogging walking for 1 min. Do this five times inbetween the inital 3 min and ending 2 min jogging.